Olin university chapter/Projects/XOBot

XOBot

Project of Olin College. Idea is to create a simple, low cost XO Robot and interface the hardware components with Turtle Art.

Status

There is now a functional prototype XOBot. The current version costs about USD175. There are already programmable robotics kits that work with the XO for that price (Namely the [[1]]). The new goal is to get the cost down to somewhere closer to USD20 and no more than USD40.

Current Prototype(12/09)

Hardware Selection

• XO
  • (+) Already available in the classroom
  • (-) heavy, requires more torque
• Casing - Sheet Metal
  • (+) cheap material
  • (+) easily/forgivably manufactured without much machinery
  • (+) designs can easily be distributed and reproduced via the internet or mailing full-size schematics
  • (-) needs some work on safety - the metal is not sharp enough to cut but is sharp enough to scratch. It would be nice to eventually make this a plastic part
  • (-) conductive - we placed a non-conductive coating (duct tape) on the bottom so as not to ruin the electronics. Another solution would be to have a plastic electronics box
• Batteries - XO batteries
  • (+) available where there are XO's
  • (+) can be recharged by placing them in the XO
  • (+) enough power to move the bot
  • (-) requires disassembling a computer, or coming up with a better solution for connecting power terminals - we used part of the bottom plate of the XO to ensure a good connection
• Microcontroller: Arduino Diecimila
  • (+) easy to use
  • (-) a bit expensive - might move towards a plain ATMega168 or 328 in a low-cost version, although that makes do-it-yourself XOBot's a little more challenging
• Motor Shield: Ardumoto(uses L298)
  • (+) just works - basically this was a time-saver
  • (-) expensive - We'll definitely make our own motor shield from plain L298's in the next version
• 2 Motors: Beetle B104
  • These motors worked fine, but were expensive because the robot was heavy. We're moving towards eliminating the XO from robot and either pre-program the robot or use a wireless connection to send commands.
  • We also considered modified RC Servos, but were concerned they wouldn't have enough torque to move the robot.
• Wheels - Lite Flite foam wheels
  • (+) again these worked very well with only a few small issues
  • (-) required some hacking to connect to our hubs
  • (-) picked up dirt from the ground
• Hubs
• Rear axel
  • We don't have one yet. Probably will just get some metal rod
• Miscellaneous screws, USB cord, plastic connectors

CAD of the XO

Hard(er) to CAD interfacing parts (the Bot kit itself) without a CAD of the XO.

Check out XOCad !!!

CAD of the Bot Kit

Schematic drawing

CAD Files